Examination of the ocean as a source for atmospheric microplastics

Abstract

Global plastic litter pollution has been increasing alongside demand since plastic products gained commercial popularity in the 1930's. Current plastic pollutant research has generally assumed that once plastics enter the ocean they are there to stay, retained permanently within the ocean currents, biota or sediment until eventual deposition on the sea floor or become washed up onto the beach. In contrast to this, we suggest it appears that some plastic particles could be leaving the sea and entering the atmosphere along with sea salt, bacteria, virus' and algae. This occurs via the process of bubble burst ejection and wave action, for example from strong wind or sea state turbulence. In this manuscript we review evidence from the existing literature which is relevant to this theory and follow this with a pilot study which analyses microplastics (MP) in sea spray. Here we show first evidence of MP particles, analysed by μRaman, in marine boundary layer air samples on the French Atlantic coast during both onshore (average of 2.9MP/m 3) and offshore (average of 9.6MP/ m 3) winds. Notably, during sampling, the convergence of sea breeze meant our samples were dominated by sea spray, increasing our capacity to sample MPs if they were released from the sea. Our results indicate a potential for MPs to be released from the marine environment into the atmosphere by sea-spray giving a globally extrapolated figure of 136000 ton/yr blowing on shore. Missing plastic in the marine microplastic models Since the first evidence of anthropogenic plastic litter affecting sea birds in the 1960's [1,2] there has been a steadily growing awareness that plastics are becoming a major pollutant. According to the plastic industries figures, around 359 million tons of plastic was manufactured globally in 2018 (up from 334 million tons in 2016) [3], of which 60 million tons were produced in Europe. Mattsson et al. (2015) estimate that around 10% of all plastic produced is lost to the sea each year [4]. A 2010 estimation suggests between 4.8-12.7 million tons of plastic entered the oceans from coastal and terrestrial areas, with up to 92% of this being <4.75mm in size [5].

Sensitivity of warm clouds to large particles in measured marine aerosol size distributions – a theoretical study

“…Many of these models use a "typical", "widemarine", or "narrow-continental" size distribution that does not account for the natural variability in aerosol size distributions or reflect their complexity. Additionally, with the mounting evidence of microplastic particles, with sizes between 4-188 µm, present in the atmosphere and in rain (Allen et al, 2020;Brahney et al, 2020), it is of greater importance to include and further study the impact of particles with D p > 10 µm on cloud and precipitation.…”

“…Aerosols influence cloud processes by serving as cloud condensation nuclei (CCN) on which cloud droplets can form (Köhler, 1936). The size of CCN determines the droplets' initial size distribution and hence impacts cloud processes and properties, such as size (Rosenfeld et al, 2008;Altaratz et al, 2014;Koren et al, 2014), lifetime (Albrecht, 1989), optical properties (Twomey and Squires, 1959;Twomey, 1977;Mülmenstädt and Feingold, 2018), and rain amounts and patterns (Yin et al, 2000b;Rosenfeld et al, 2006;Xue et al, 2008;Yuan, 2011;Altaratz et al, 2014;Koren et al, 2014;Seigel, 2014).…”

Environment and COVID-19: Pollutants, impacts, dissemination, management and recommendations for facing future epidemic threats

“…Along with plastic waste, disposable masks can reach land and aquatic systems, where animals may become entangled or eat them by mistake ( Sigler, 2014 ; Vegter et al, 2014 ). Recent evidence has shown that microplastics can reach remote regions of the planet, and also end up in our bodies through food intake and breathing ( Allen et al, 2020 ).…”

The Story of Plastic Pollution: From the Distant Ocean Gyres to the Global Policy Stage

“…The atmosphere is thus clearly a transport pathway for microplastics to reach the ocean. Recent work also suggests that the atmosphere may also be a pathway for microplastics to exit the ocean via bubble burst ejection and wave action (Allen et al, 2020). As such, mass balance estimates must consider atmospheric transport as pathways both into and out of the ocean.…”